Oh, first contact... so many choices... Vulcans would be interesting.
If we're going after ANYTHING as a potential alien species though, finding Equestria would be nice. No, I'm not kidding. Benevolent diarchy with communism/socialism that actually WORKS, finding what you're good at and being able to enjoy what you do for a living for the rest of your life? magic? being able to actually TALK to the resident deities? Sign me up.